Thursday, 15 January 2015

1. Define UNIX?* To develop an o/s that could serve a large community of users & allow them to share data whenever they require.2. Define Linux?* It is a freely distributed implementation of Unix like kernel, the low level core of an o/s.3. What is an Operating System?* It is a s/w program design to act as an interface b/w user & the computer.4. List types of o/s?* Single user o/s, Multi user o/s, Network o/s.

5. Define features of Linux?* Multi user capability, Multi task capability,Communication, Security, Portable.6. What is Kernel & Shell?* Kernel is an o/s that provides services like file s/m , memory mgt, CPU scheduling, I/O mgt.* Shell is an mediator or command interpreter.7. List types of Shells?* Bourne shell, C shell, Korn shell.8. Define Vi editor?* Vi is text editor.9. List modes of vi editor?* Command mode, Insert mode, Exit mode.10. What is Process?* A program in execution.11. List types of Process Status?* Fore ground process, Back ground process.12. Define awk?* It is a powerful native text & manipulation utility.13. What is sed?* It is a stream editor & multipurpose tool which combines the work of several filters.14. What is Script?* It is a textual form.15. Define Shell Script?*A group of commands which stored in one file called Shell script.16. Define pipe?* It is a buffer & stores o/p of one action as an i/p to another action.17. List i/p & o/p redirections?* Standard i/p, Standard o/p, Standard error.18. Define Stream& Here document?* It is simply a sequence of bytes.* It is a way of passing i/p to a cmd from a shell script.19. What are Shell MetaCharacters?* File name Substitution, I/O Redirection,Process Execution, Quoting Meta characters,Positional parameters, Special characters.20. Define Shell Variable?*It provides ability to store & manipulate information with in the shell program.21. List types of Variables?* System defined variable & User defined variable.22. List types of test command?* Numerical test, String test, File test.23. List types of Control structures?* Selection/Decision, Repetition/Loop, Case-esac.24. What is Arithmetic shell script?* It is used for performing arithmetic operations.25. What is Interactive shell script?* It is used for reading operations.26. Define Interrupt process?* It states that shell script will terminate when ever the interrupt key is pressed.27. What is purpose of using ‘trap’ cmd?* It is used to stop Program execution.28. Define Function?*It is used to execute a group of statements as bunch.29. Define File?* File is a collection of information storing in a container. (Or) It is a collection of records.30. What are the categories of files?* Ordinary/regular, Directory, Device files.31. List Block Types?*Boot block, Super block, Data block, Inode block.32. List File Types?* Regular, Directory, Character special,Block special, FIFO, Socket, Symbolic link files.33. List Standard I/O & Stream error functions?* Std I/O: fopen,fclose,fflush,fseek,fgetc,getc,getchar,fputc,putc,putchar,fgets,gets,fread,fwrite.* Std Error: feof,ferror,clearerr.34. What are Formatted I/O functions?* I/p: scanf,fscanf,sscanf.* O/p: printf,fprintf,sprintf & printf,vfprintf,vsprintf.35. Define System call?* It is an interface b/w process & kernel.36. Define Library Function?* It invokes appropriate kernel services.37. What is the difference b/w s/m call & library function?* S/m calls are part of kernel but Library functions are part of linux super structure.38. Define File Descriptor?* It is a non –ve integer,depending on permission kernel has to create file descriptor.39. What are Low level file access permissions?* creat,open,read,write,close,lseek,stat,fstat,lstat,access,umask,ioctl,dup/dup1,dup2, fcntl.40. List File & directory management functions?*mkdir,rmdir,chdir,geetcwd,link,unlink,symlink,chmod,chown.41. What is difference b/w Hard link & Soft link?* Hard link is direct pointer to a file, but Soft linkis indirect pointer to a file.42. List Directory handling system calls?* Opendir, readdir, closedir, rewinddir, seekdir, telldir.43. What is File locking & Record locking?* File locking locks on entire file where record locking allows a processor to lock a specified portion of a file.44. List types of locking?* Advisory locking & Mandatory locking.45. What is process image?* It contains user program, user data, stack, PCB.46. Define PCB?* Process control block is used to control process states.47. Define process attributes?* Process has a series of characteristics which are called as a process attributes.48. List process states?* Ready, Execution, Suspend, Stopped, Zombie.49. Define Zombie process?* The child process terminates while before the parent dies.50. Define Orphan process?* The parent process wants to terminate before the child process.51. List process management functions?* fork,vfork,exit,wait,waitpid,exec family ,system.52. What is vfork?* It is a virtual fork.53. Define Signal?* Signal is a software interrupt.54. Define Reliable signal?* Signal is generated by process when event occurs that causes the signal occurs.55. Define Unreliable signal?* Signals that cannot be identified.56. What is IPC?* Inter process communication describes different ways of msg passing b/w different processes that are running on some o/s.57. List methods of IPC?* Pipes, FIFO’s, Msgqueues, Semaphores, Shared m/y.58. List types of pipes?* Unidirectional & Bidirectional pipes.59. What is unidirectional pipe?* Single directional flow of data.60. What is Bidirectional pipe?* Bi directional flow of data.61. Define FIFO?*FIFO/Named pipe is a permanent fixture.62. Define Message Queue?* It describes storing of data in a orbitary order.63. Define Semaphore?* Semaphore is synchronization primitive.64. Define Shared Memory? * It provides a way around this by letting twoor more processes shared a memory segment.65. Define Socket?* It is a local network of a people with outside world process.66. List Linux API’s of messages?*msgget, msgsnd, msgrcv, msgctl.67. List Linux API’s of semaphores?* Semget, semop, semctl68. List Linux API’s of shared memory?* Shmget, shmat, shmdt, shmctl.69. Define Thread?* Multiple strands of execution in a single program .70. Define light weight process?* It can be viewed as a mapping b/w user threads & kernel threads.71. List POSIX threads API’s?* Creating threads, Thread semaphores, Thread mutexes, Thread attributes, cancelling a thread.72. Define Mutex?* Which act as an mutual exclusion device to protect sections of code.73. List Thread attributes?* detached state,sched policy,sched param,inherit sched,scope,stack size.74. List Socket s/m call for connection oriented protocol?* socket, bind,listen,accept,connect,read,write.75. List Socket s/m call for connection less protocol?* socket,bind,sendto,recvfrom.